1. Technical Field
This invention is related to the field of integrated circuit implementation, and more particularly to the implementation of memories.
2. Description of the Related Art
Computing systems may include one or more systems on a chip (SoC), which may integrate a number of different functions, such as, graphics processing, onto a single integrated circuit. With numerous functions included in a single integrated circuit, chip count may be kept low in mobile computing systems, such as tablets, for example, which may result in a smaller form factor for such mobile computing systems.
Memories, such as those included in SoC designs, typically include a number of data storage cells arranged in an array, and composed of transistors fabricated on a semiconductor substrate. Such data storage cells may be constructed according to a number of different circuit design styles. For example, the data storage cells may be implemented as a single transistor coupled to a capacitor to form a dynamic storage cell. Alternatively, cross-coupled inverters may be employed to form a static storage cell, or a floating gate metal-oxide semiconductor field-effect transistor (MOSFET) may be used to create a non-volatile memory.
As semiconductor process technology has continued to evolve, thicknesses of various insulating layers on a semiconductor have reduced in response to smaller device geometries. In order to accommodate such insulating layers, power supply voltages have been lowered to limit the strain resulting from electric fields applied across the insulating layers. Moreover, the smaller device geometries may result in additional device-to-device variation in the electrical characteristics of MOSFETs within an integrated circuit due to differences in lithography, dopant levels, and the like.
In some cases, power supply voltages have been reduced to the point where some circuits do not perform as intended, or margin previously present in a circuit design may no longer be available. Memories, such as those described above, may be sensitive to these lower power supply voltages. Lower power supply voltages in conjunction with manufacturing variation in MOSFETs within a memory, may result in memory sub-circuits, such as, e.g., sense amplifiers or data storage cells, not operating as intended.